Buggy smartmatch on tied array?

[SankoR]

Still working through old reported issues and think I have another upstream bug. Take this:

use Tie::Array;
tie my @array_t, 'Tie::StdArray';
my @array = @array_t = qw[aaa bbb ccc ddd eee];
print "plain smatch: " . (/a/ ~~ @array) . "\n";
print "plain grep:   " . (grep {/a/} @array) . "\n";
print "tied smatch:  " . (/a/ ~~ @array_t) . "\n";
print "tied grep:    " . (grep {/a/} @array_t) . "\n";

When run on my v5.16.3 install, the smartmatch doesn't correctly match against the magically tied @array_t. Devel::Trace shows that it calls the array's FETCHSIZE method just like the tied grep but never bothers to FETCH the correct values. So, I end up with output that looks like:

Use of uninitialized value in pattern match (m//) at bugs.t line 6.
Use of uninitialized value in pattern match (m//) at bugs.t line 6.
Use of uninitialized value in pattern match (m//) at bugs.t line 6.
Use of uninitialized value in pattern match (m//) at bugs.t line 6.
Use of uninitialized value in pattern match (m//) at bugs.t line 6.
plain smatch: 1
plain grep:   1
tied smatch:  
tied grep:    1

The warnings are obviously from smartmatch trying to match against undefined values. Can anyone verify that I'm not 'doing it wrong' before I submit a bug report to p5p?

Update: Reported as RT#120122.

[davido]

I can at least verify that it's an issue on 5.18. And the code looks reasonable to me. Of course on 5.18 I also get:

Smartmatch is experimental at ./mytest.pl line 4.
Smartmatch is experimental at ./mytest.pl line 6.

You might search the bug queue for issues related to smartmatch to see if it's already been reported. If not, go for it. I think the operator is in a state of flux, but it would be a shame for little things like this to not get fixed if the operator ever has its experimental designation removed again.

[ikegami]

It's probably a trivial thing to fix, and it will be. Smart match is experimental because it has major design issues.

[kcott]

G'day SankoR,

On 5.18.1 (current version):

$ cat junk
#!/usr/bin/env perl

use strict;
use warnings;
no if $] >= 5.018, warnings => 'experimental::smartmatch';

use Tie::Array;
tie my @array_t, 'Tie::StdArray';
my @array = @array_t = qw[aaa bbb ccc ddd eee];
print "plain smatch: " . (/a/ ~~ @array) . "\n";
print "plain grep:   " . (grep {/a/} @array) . "\n";
print "tied smatch:  " . (/a/ ~~ @array_t) . "\n";
print "tied grep:    " . (grep {/a/} @array_t) . "\n";

$ junk
plain smatch: 1
plain grep:   1
Use of uninitialized value in pattern match (m//) at ./junk line 12.
Use of uninitialized value in pattern match (m//) at ./junk line 12.
Use of uninitialized value in pattern match (m//) at ./junk line 12.
Use of uninitialized value in pattern match (m//) at ./junk line 12.
Use of uninitialized value in pattern match (m//) at ./junk line 12.
tied smatch:  
tied grep:    1